Many mobile devices, such as cellular telephones, personal digital assistants (PDAs), and other handheld computing and communicating devices, advantageously employ a keyboard or keypad as a means of inputting data into the device.
Existing keyboards or keypads for small handheld devices often include a standard 12-key telephone keypad. Typing text using such a keypad requires the user to input data in an unfamiliar manner. Other kinds of keyboards follow the standard Dvorak keyboard layout or, more commonly, the QWERTY keyboard layout and are used in portable handheld devices such as the RIM 950 Wireless Handheld™. This kind of keyboard, when adapted to a mobile device, uses a plurality of small individual keys optimised for operation with the thumbs of the user.
However, such a keyboard has considerably more keys than a standard telephone keypad and the larger number of individual keys requires more space on a printed circuit board (PCB) than a keypad. Each key requires its own footprint and switch, such as a dome switch, on the PCB that activates a function or input when a key is depressed. Because of the relatively small size of such handheld devices, PCB space is limited and a QWERTY or Dvorak type keyboard takes up valuable real estate on the PCB. Keyboard size is limited by the distance between the dome switches, which have a minimum distance between them. The cost of dome switches is not insignificant when a keyboard includes a large number of keys. It is therefore desirable to provide an improved keyboard assembly for an electronic device.